Changes in plasma and erythrocyte fatty acids in patients fed enteral formulas containing different fats

Intravenous fish oil lipid emulsions in critically ill patients: an updated systematic review and meta-analysis

INTRODUCTION

Intravenous fish oil (FO) lipid emulsions (LEs) are rich in ω-3 polyunsaturated fatty acids, which exhibit anti-inflammatory and immunomodulatory effects. We previously demonstrated that FO-containing LEs may be able to decrease mortality and ventilation days in patients who are critically ill. Since 2014, several additional randomized controlled trials (RCTs) of FO-containing LEs have been published. Therefore, the purpose of this systematic review was to update our previous systematic review with the aim of elucidating the efficacy of FO-containing LEs on clinical outcomes of patients who are critically ill.

METHODS

We searched electronic databases from 1980 to 2014. We included four new RCTs conducted in critically ill adult patients in which researchers evaluated FO-containing LEs in parenterally or enterally fed patients.

RESULTS

A total of 10 RCTs (n = 733) met inclusion criteria. The mean methodological score was 8 (range, 3 to 12). No effect on overall mortality was found. When we aggregated the results of five RCTs in which infections were reported, we found that FO-containing LEs significantly reduced infections (risk ratio (RR) = 0.64; 95% confidence interval (CI), 0.44 to 0.92; P = 0.02; heterogeneity I (2) = 0%). Subgroup analysis demonstrated that predominantly enteral nutrition-based trials showed a tendency toward a reduction in mortality (RR = 0.69; 95% CI, 0.40 to 1.18; P =0.18; heterogeneity I (2) =35%). High-quality trials showed a significant reduction in hospital length of stay (LOS) (weighted mean difference = -7.42; 95% CI, -11.89 to -2.94; P = 0.001), whereas low-quality trials had no effect (P = 0.45). The results of the test for subgroup differences in hospital LOS was significant (P = 0.001).

CONCLUSION

FO-containing LEs may be associated with a reduction in infections and also could be associated with a reduction in duration of ventilation and hospital LOS. Further large-scale RCTs are warranted and should be aimed at consolidating potential positive treatment effects.

Alternative lipid emulsions in the critically ill: a systematic review of the evidence

PURPOSE

Parenteral lipid emulsions (LEs) are commonly rich in long-chain triglycerides derived from soybean oil (SO). SO-containing emulsions may promote systemic inflammation and therefore may adversely affect clinical outcomes. We hypothesized that alternative oil-based LEs (SO-sparing strategies) may improve clinical outcomes in critically ill adult patients compared to products containing SO emulsion only. The purpose of this systematic review was to evaluate the effect of parenteral SO-sparing strategies on clinical outcomes in intensive care unit (ICU) patients.

METHODS

We searched computerized databases from 1980 to 2013. We included randomized controlled trials (RCTs) conducted in critically ill adult patients that evaluated SO-sparing strategies versus SO-based LEs in the context of parenteral nutrition.

RESULTS

A total of 12 RCTs met the inclusion criteria. When the results of these RCTs were statistically aggregated, SO-sparing strategies were associated with clinically important reductions in mortality (risk ratio, RR 0.83; 95 % confidence intervals, CI 0.62, 1.11; P = 0.20), in duration of ventilation (weighted mean difference, WMD -2.57; 95 % CI -5.51, 0.37; P = 0.09), and in ICU length of stay (LOS) (WMD -2.31; 95 % CI -5.28, 0.66; P = 0.13) but none of these differences were statistically significant. SO-sparing strategies had no effect on infectious complications (RR 1.13; 95 % CI 0.87, 1.46; P = 0.35).

CONCLUSION

Alternative oil-based LEs may be associated with clinically important reductions in mortality, duration of ventilation, and ICU LOS but lack of statistical precision precludes any clinical recommendations at this time. Further research is warranted to confirm these potential positive treatment effects.

Parenteral fish oil lipid emulsions in the critically ill: a systematic review and meta-analysis

INTRODUCTION

ω-3 Polyunsaturated fatty acids contained in fish oils (FO) possess major anti-inflammatory, antioxidant, and immunologic properties that could be beneficial during critical illness. We hypothesized that parenteral FO-containing emulsions may improve clinical outcomes in the critically ill.

METHODS

We searched computerized databases from 1980-2012. We included randomized controlled trials (RCTs) conducted in critically ill adult patients that evaluated FO-containing emulsions, either in the context of parenteral nutrition (PN) or enteral nutrition (EN).

RESULTS

A total of 6 RCTs (n = 390 patients) were included; the mean methodological score of all trials was 10 (range, 6-13). When the results of these studies were aggregated, FO-containing emulsions were associated with a trend toward a reduction in mortality (risk ratio [RR], 0.71; 95% confidence interval [CI], 0.49-1.04; P = .08; heterogeneity I (2) = 0%) and a reduction in the duration of mechanical ventilation (weighted mean difference in days [WMD], -1.41; 95% CI, -3.43 to 0.61; P = .17). However, this strategy had no effect on infections (RR, 0.76; 95% CI, 0.42-1.36; P = .35) and intensive care unit length of stay (WMD, -0.46; 95% CI, -4.87 to 3.95; P = .84, heterogeneity I (2) = 75%).

CONCLUSION

FO-containing lipid emulsions may be able to decrease mortality and ventilation days in the critically ill. However, because of the paucity of clinical data, there is inadequate evidence to recommend the routine use of parenteral FO. Large, rigorously designed RCTs are required to elucidate the efficacy of parenteral FO in the critically ill.

Immune-enhancing enteral diet increases blood flow and proinflammatory cytokines in the rat ileum

BACKGROUND

Enteral feeding improves outcome following surgery. Benefits depend on timing, route (enteral vs parenteral), and nutrient composition (standard vs immune-enhancing diets; IED). IED augments intestinal immunity and stimulates gut blood flow during absorption in a nutrient-specific manner. We hypothesize that a mechanism for the gut protective effect of IED is augmentation of blood flow to the gut-associated lymphoid tissue (GALT) in the terminal ileum.

METHODS

Male Sprague-Dawley rats (200-230 g) were fed for 5 days either an IED (Impact, Novartis) or an isocaloric, isonitrogenous control diet (CD, Boost, Mead-Johnson) matched to the daily caloric intake (rat chow). Rats were then anesthetized and cannulated for microsphere determination of whole organ blood flow. Blood glucose levels and blood flow to abdominal organs were determined at baseline and 30, 60, 90, and 120 min after gastric gavage (2 ml) with IED or CD. Intestinal tissues were harvested for cytokine levels (ELISA: IL-4, IL-10, IFN-gamma, and IgA).

RESULTS

Chronic IED increased baseline blood flow in the distal third of the small intestine compared to chow-fed and CD. Baseline blood flow was comparable between IED and CD in all other organs. CD and IED produced different blood flow patterns after gavage. CD increased blood flow compared to baseline and IED in antrum, duodenum, and jejunum. Ileal blood flow remained elevated in IED rats for 2 h, perhaps suggesting maximal blood flow. IED increased blood glucose compared to CD. Chronic IED increased IL-4 and decreased IL-10 in the terminal ileum.

CONCLUSIONS

Chronic IED exposure increases and sustains ileal blood flow compared to CD with altered proinflammatory cytokine expression. Our data suggest that a mechanism for the IED effect involves the selective perfusion of the terminal ileum and contiguous GALT during IED nutrient absorption.

Omega-3 fatty acids in immune-enhancing enteral diets selectively increase blood flow to the ileum by a bile acid dependent mechanism

BACKGROUND

The immune-enhancing diet (IED) (Impact, Novartis Corp, Minneapolis, Minn) initiates a delayed and sustained increase in blood flow to the ileum and gut-associated lymphoid tissue. The immune-enhancing benefits of Impact (Novartis Corp) are attributed to the addition of L-arginine, fish oil (FO), and RNA fragments to a standard enteral diet. The sustained increase in blood flow to the gut-associated lymphoid tissue during IED exposure might account for these immune effects. We hypothesized that the increase in ileal blood flow with IED might be a result of ileal omega-3 fatty acid absorption in the ileum by a bile-dependent mechanism.

METHODS

Male Sprague-Dawley rats (200 g-230 g) were anesthetized and cannulated for microsphere measurement of whole organ blood flow. Rats received gastric gavage (2 mL) with either IED, an isocaloric, isonitrogenous control diet (CD) (Boost, Mead-Johnson, Evansville, Ind), CD plus menhaden FO (CD+FO), or CD+FO plus bile duct ligation (BDL). Blood flow was determined at baseline and 30, 60, and 120 minutes after short-term gavage.

RESULTS

Baseline blood flow and central hemodynamics were comparable in all groups. In the ileum, at 120 minutes postgavage, blood flow was increased by IED and CD+FO compared with baseline and CD. BDL prevented the increase in blood flow in the CD+FO+BDL rats. All groups exhibited differences in splanchnic blood flow distribution after gavage: CD and CD+FO+BDL increased blood flow compared with baseline early in the proximal gut and spleen. IED and CD+FO produced a delayed, sustained hyperemia to the distal gut.

CONCLUSIONS

Gastrointestinal blood flow distribution after feeding is dependent on nutrient composition. These findings suggest that omega-3 fatty acids are the components of the enteral IED, Impact (Novartis Corp), which produce the increased blood flow to the terminal ileum and its contiguous gut-associated lymphoid tissue. Our data suggests that an intact enterohepatic bile pathway is needed for the IED blood flow effect.

Immune-enhancing enteral diet selectively augments ileal blood flow in the rat

BACKGROUND

Clinical studies show that immune-enhancing enteral diets (IED; with L-arginine, fish oil, and RNA fragments) decrease the rate of sepsis and shorten the length of hospital stay after the start of enteral feeding. These beneficial effects are dependent on the route of administration (enteral vs parenteral) and on the nutrient composition (IED vs standard diets). Gut exposure to an IED seems to preserve and/or augment intestinal mucosal immunity. However, nutrient absorption stimulates gut blood flow in a nutrient-specific manner (i.e., postprandial hyperemia). We hypothesized that an IED would initiate a different pattern of whole organ blood flow compared to a standard diet. This suggests that a mechanism for the protective effect of IED might be the preferential augmentation of gut blood flow to gut-associated lymphoid tissue (GALT) or mucosa-associated lymphoid tissue (MALT).

METHODS

Male Sprague-Dawley rats (200-225 g) were anesthetized and cannulated for colorimetric microsphere determination of blood flow distribution (with the phantom organ technique). Animals received gastric gavage (2 ml) of an IED (Impact; Novartis) or an isocaloric, isonitrogenous control diet (Boost; Mead-Johnson). Blood flow to the antrum, duodenum, jejunum, ileum, colon, liver, kidneys, and spleen was determined at baseline and 30, 60, 90, and 120 min after gavage.

RESULTS

Baseline blood flows to the left and right kidneys were within 10%, indicating the technical integrity of the microsphere technique and assay. Control diet augmented blood flow compared to IED in the antrum, duodenum, jejunum, and spleen. Conversely, IED gavage stimulated a delayed and sustained hyperemic response in the ileum. IED also increased hepatic blood flow early (30 min). IED increased blood glucose levels compared to control diet at 30, 60, and 90 min, suggesting enhanced nutrient absorption.

CONCLUSIONS

These data show that blood flow distribution depends on nutrient composition and that IED preferentially augments blood flow to the ileum. Since the terminal jejunum and ileum contain much of the GALT, our data suggest that a mechanism for enterally stimulated mucosal immunity involves selective perfusion of the terminal ileum during IED nutrient absorption.

Enteral nutrition

This article briefly reviews the literature supporting the use of enteral nutrition, which appears to be the preferred method of nutritional support in critically ill patients. Patients who benefit the most from this type of support, as well as the administration and route preferences in enteral nutrition, are discussed. In addition, the different types of enteral formulas and the more frequently associated complications that occur with tube feedings are reviewed.

Metabolic characteristics of healthy adult males as affected by ingestion of a liquid nutritional formula containing fish oil, oligosaccharides, gum arabic and antioxidant vitamins

n-3 Fatty acids from fish oil and short-chain fatty acids produced from fermentation of oligosaccharides may attenuate a portion of gut injury and inflammation associated with ulcerative colitis. The purpose of this study was to assess the effects of an enteral nutritional formula containing supplemental oligosaccharides, gum arabic and fish oil on serum metabolite profiles, haematology, plasma and red blood cell membrane phospholipid fatty acid profiles, urinary constituent, and safety in healthy human adult males. 30 subjects were randomly assigned to one of two treatments, a control formula (n = 10) and an ulcerative colitis nutritional formula (UCNF; n = 20). Formulas contained comparable levels of protein, fat and non-structural carbohydrates. Daily intake of the formulas provided nutrients to meet or exceed the recommended daily allowance. Intake was recorded daily while blood and urine samples were collected weekly on days 0, 7 and 14. Certain subjects consuming large quantities of the UCNF experienced some abdominal distention, gas and loose stools. Sole source intake of the UCNF was safe over 14 days as assessed by routine measurements of serum metabolite profiles, haematology and urinalysis compared with subjects fed the control formula. Substantial decreases in plasma and red blood cell phospholipid 18:2n-6 and increases in 20:5n-3 and 22:6n-3 within 1 wk of feeding the UCNF were noted.

Fish oil-supplemented feeding does not attenuate warm liver ischemia and reperfusion injury in the rat

Liver ischemia and reperfusion injury is mediated by oxygen free radicals, cytokines, and prostanoids produced by Kupffer cells and infiltrating neutrophils. Fish oil-supplemented diets alter membrane phospholipid composition and modify prostanoids and cytokine production in response to ischemia and reperfusion. This study tested the hypothesis that a fish oil-supplemented diet would attenuate warm liver ischemia and reperfusion injury in the rat. Male Sprague-Dawley rats were fed Vital HN supplemented with either fish oil (FO) or corn oil (CO) by the continuous duodenal infusion for 5 days. Total dietary fat (26% of total calories), caloric intake (70 cal/day), and volume (60 ml/day) were identical between two groups. Plasma eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) levels increased significantly in rats fed fish oil (0 to 16.3% for EPA and 2 to 12% for DHA). Liver histology was similar in both groups before ischemia. On Day 6, rats were subjected to 60 min of reversible hepatic ischemia. Plasma TNF levels, 1 and 24 hr after reperfusion, were not different between FO and CO rats. Liver injury assessed by bile flow, histology, plasma ALT, and bile glutathione efflux did not differ between groups. We conclude that our fish oil-supplemented enteral diet does not attenuate warm liver ischemia and reperfusion injury in rats.

An enteral formula containing fish oil, indigestible oligosaccharides, gum arabic and antioxidants affects plasma and colonic phospholipid fatty acid and prostaglandin profiles in pigs

Evidence supports a pathogenic role of arachidonic acid-derived inflammatory mediators within the gastrointestinal tract of patients with inflammatory bowel disease. The purpose of this study was to assess the effects of an ulcerative colitis nutritional formula (UCNF) containing oligosaccharides, fish oil, gum arabic and antioxidants on plasma and colonic phospholipid fatty acid and prostaglandin profiles in pigs. Twenty-four growing barrows in two replications were equally randomized among four killing times (d 0, 7, 14 and 21), and one of two diets, a control and the UCNF. Diets contained comparable levels of protein, fat, and nonstructural carbohydrate and met 100% of the energy requirements of the pig. Intake and body weight were recorded daily while blood, urine and tissue samples were collected at time of kill. Within 1 wk of ingestion of the UCNF, the composition of plasma phospholipid fatty acids showed an increase in 20:5(n-3) and 22:6(n-3) (P < 0.0001) and a decrease in 20:4(n-6) and 18:2(n-6) (P < 0.0001). Similar effects were observed for the phospholipids in the colonic and cecal mucosa. Plasma prostaglandin E was unaffected by treatment, whereas thromboxane B2 and 6-keto-prostaglandin F1 alpha levels were significantly decreased after 7 d of UCNF ingestion. Ingestion of the UCNF resulted in a suppression in the synthesis of proinflammatory prostaglandins by cecal and colonic mucosal cells. Levels of colonic and cecal prostaglandin E, 6-keto-prostaglandin F1 alpha and thromboxane B2 were significantly decreased after 7 d of UCNF ingestion. These changes may have been mediated by rapid increases of (n-3) fatty acids into cellular phospholipids. Dietary supplementation with the UCNF may prove beneficial for patients with ulcerative colitis by modulating colonic prostaglandin synthesis.

Early enteral feeding in postsurgical cancer patients. Fish oil structured lipid-based polymeric formula versus a standard polymeric formula

OBJECTIVES

The authors compared the safety, gastrointestinal tolerance, and clinical efficacy of feeding an enteral diet containing a fish oil/medium-chain triglyceride structured lipid (FOSL-HN) versus an isonitrogenous, isocaloric formula (O-HN) in patients undergoing major abdominal surgery for upper gastrointestinal malignancies.

SUMMARY BACKGROUND DATA

Previous studies suggest that feeding with n-3 fatty acids from fish oil can alter eicosanoid and cytokine production, yielding an improved immunocompetence and a reduced inflammatory response to injury. The use of n-3 fatty acids as a structured lipid can improve long-chain fatty acid absorption.

METHODS

This prospective, blinded, randomized trial was conducted in 50 adult patients who were jejunally fed either FOSL-HN or O-HN for 7 days. Serum chemistries, hematology, urinalysis, gastrointestinal complications, liver and renal function, plasma and erythrocyte fatty acid analysis, urinary prostaglandins, and outcome parameters were measured at baseline and on day 7. Comparisons were made in 18 and 17 evaluable patients based a priori on the ability to reach a tube feeding rate of 40 mL/hour.

RESULTS

Patients receiving FOSL-HN experienced no untoward side effects, significant incorporation of eicosapentaenoic acid into plasma and erythrocyte phospholipids, and a 50% decline in the total number of gastrointestinal complications and infections compared with patients given O-HN. The data strongly suggest improved liver and renal function during the postoperative period in the FOSL-HN group.

CONCLUSION

Early enteral feeding with FOSL-HN was safe and well tolerated. Results suggest that the use of such a formula during the postoperative period may reduce the number of infections and gastrointestinal complications per patient, as well as improve renal and liver function through modulation of urinary prostaglandin levels. Additional clinical trials to fully quantify clinical benefits and optimize nutritional support with FOSL-HN should be undertaken.

Dietary fish oil and cytokine and eicosanoid production during human immunodeficiency virus infection

BACKGROUND

Dietary fish oil (FO) has been shown to modulate the immune system. The purpose of this study was to explore the effects of FO supplementation on the production of dienoic eicosanoids and cytokines in patients with human immunodeficiency virus (HIV) infection.

METHODS

This was a randomized, prospective, double-blind study that included homosexual males with HIV infection. Patients were asked to consume voluntarily five food bars daily containing FO (n = 10) or safflower oil (SO) (n = 9) for 6 weeks. At baseline and week 6, plasma was obtained to measure incorporation of omega-3 fatty acids. At baseline, week 3, and week 6, measurements were made of changes in dienoic eicosanoids and cytokines from lipopolysaccharide (LPS)-stimulated peripheral blood mononuclear cells (PBMC) or spontaneously releasing cells.

RESULTS

In the FO group but not the SO group, there was increased incorporation of the omega-3 fatty acid docosahexaenoic acid (DHA) into the phospholipids of the fatty acids of the plasma. In the FO group, there was a significant decrease (p = .01) in 6-keto prostaglandin (PG) F1 alpha released from PBMC. There was a significant increase (p = .01) in interleukin (IL)-6 released from the PBMC in the FO group between baseline and week 3 and between week 3 and week 6. At week 6, there was significantly more IL-6 (p = .01) released from the PBMC in the FO group compared with the SO group. There was no change in CD4 cell counts by analysis of variance.

CONCLUSIONS

The FO-containing food bars were well tolerated and allowed incorporation of omega-3 fatty acids to occur. Despite evidence of significant metabolic effects on eicosanoid and cytokine production, widespread clinical use of FO for HIV-infected patients is not warranted without further study, particularly given the trend toward a decline in CD4 cell numbers at this dose and with this type of fish oil.

Fatty acid composition of lung, macrophage and surfactant phospholipids after short-term enteral feeding with n-3 lipids

Utilization of enteral feeding modalities may prove clinically relevant for rapid modulation of lung phospholipid polyunsaturated fatty acids (PUFA) that serve as substrates for the formation of vasoactive dienoic eicosanoids. We compared the effects of short-term enteral feeding with formulations enriched with either fish (n-3) or corn (n-6) oil PUFA on the fatty acid composition of rat lung, alveolar macrophage and surfactant phospholipids. The diets were infused continuously for 72 h through a surgically placed gastroduodenal feeding catheter by a syringe pump. The n-3 PUFA derived from the fish oil enriched diet were readily incorporated into the phospholipid membranes of the alveolar macrophages, lung tissue and pulmonary surfactant. The relative percentages of the n-3 PUFA were significantly higher and individual and total n-6 PUFA significantly lower in the macrophage, lung and surfactant phospholipids from the n-3-supplemented rats in comparison with those present in the rats infused enterally with the n-6 diet or untreated, chow-fed rats (baseline). In contrast, there was a significant increase in linoleic acid (18:2n-6) without modification of arachidonic acid (20:4n-6) in the alveolar macrophages, lung tissue and surfactant from rats enterally receiving the n-6 diet relative to levels measured in the rats at baseline. The results suggest that short-term continuous delivery of n-3-enriched enteral preparations can foster rapid modification of membrane phospholipid PUFA composition of lung tissue, alveolar macrophages and lung surfactant.(ABSTRACT TRUNCATED AT 250 WORDS)